I tried searching for the past 3 hours with not much luck found some good articles but most were for stock engine conditions, i have a 91 tpi trans am with a 5 speed that i recently swapped my 355 into the car ran decent before the swap just had a dead injector which fueled the energy for the swap, the engine i swapped in has stock internals with a pretty large cam and a better set of heads with roller rockers, no egr...has a block off plate. I can't seem to get it to time correctly according to the light its constantly advanced 20-30 degrees and it runs fine like that at base timing I had the engine running fine via accel gen 6 dfi in my gta, now if i start it and keep the rpm above 1500 it runs great, if i let the rpm fall below 1500rpm the code 43 sets and then it detonates on acceleration off idle and takes a few minutes cruising before it runs good again then if i let it fall below 1500 again same thing...right now it has the 305 chip in it, 305 esc, msd dist., 350 knock sensor...not sure if I should try to diag it, swap in the accel or have a chip made...i think it is reading knock bc of the rockers or cam? but what about the base timing issue?

 

Well a code 43 is set when the ECM sees a constant knock condition in many cases as result of the wire from the ESC to the ECM being broken. Now in your case when you set the base timing to 20-30 degrees it can run like that but it wont be happy about it. ITs no supprise that the ESC is sending a constant knock signal. Also the 305 and the 350's chips are different so no matter what you do it wont run right till thats fixed so there isnt really much point in trying to do any troubleshooting just yet.

 

i know how to diag the electrical system and how the knock filter and esc work wondering about why base timing will not retard anymore because it just stalls and won't run with any less timing and swapping in a 350 chip didn't change anything want to know if the engine is too much for a stock style prom and if i need a custom prom or if something stupid is keeping me from being able to properly time it...should have posted in diy prom i guess

 

Well yea the chips physically are really the same so theres really no need to do anything aftermarket as its all the same stuff. So as long as youve done a good DIY tune it should be fine as far as the chip is concerned. Now first ide start with the easy stuff check over the ignition system make sure you dont have any wires crossed or anything like that. Next ide pull a few spark plugs to check the color. I suspect your running alittle lean as result of not compensteing for large cam.

 

yea no the wires aren't crossed and fuel pressure is at 52 just gonna have to get a gen 7 accel don't really have time to keep changing and messing with tunes and maps...

 

I'm a technician just not familiar with obd 1 can't plug into the the computer and read exactly what is going on as i could with obd2 the timing fluctuates off idle then finds the right spot and runs great until it drops back down to idle then detonates from the timing fluctuating again...gonna have to get the gen 7 so i can see what is going on...i have a gen 6 laying around but don't have a computer old enough to run calmap...